Strand or cable



Patented June 414, 194@ UNITED ETTES arts Application March 2 Claims.

This invention is particularly concerned with composite electric cables of the type which, in the interests of economy, are made from a relatively few wires intertwisted intoa strand.

' Usually, three wires are intertwisted, one of these Wires being made o steel or metal of similar strength and the other two of copper or some other metal possessing good electrical conductivity. Such a cable is not only unbalanced but is also subject to sagging because the harder wire tends to straighten and the softer wires will conform to the harder wire into a wider helix as though Wrapping around a mandrel. My object is to construct a cable that is not substantially more expensive than this three-wire type,

yet which eliminates the undesirable action just mentioned.

Accordingly, my invention contemplates a strand of relatively softer and harder intertwisted wires, the latter diametrically intercontacting and being symmetrical about the strand axis, and the softer wires being laid in the interstices between the harder wires. The intercontacting surfaces of the harder wires may be shaped to provide relatively7 large bearings, or the intercontacting surfaces of all the wires may be shaped with the same end in view.

A composite electric transmission cable -constructed according to the above principles will possess the advantage that the two harder wires bear against one another instead oi against theV other wires included because oi their electrical conductivity advantages and, therefore, necessarily made of softer metal. It follows that the wires primarily included straighten under tension, whereby deformation and creep or" the cable is retarded. l

Specific examples of the foregoing are `illustrated by the accompanying drawing which illustrates crosssections of four specific examples of possible arrangements,

Figurel being the first example;

Figure 2 the second examl Figure 3 the third example;

Figure 1; the fourth example.

More specifically, in Figure four wires, all of equal diameter, are intertwisted to produce a cable, the Wires l being ma le oi steel and arnged to dianietrically s and the other two wires, numeraled being made of copper and carried in the interstices between the two first mentioned wires. Metals other than copper may be used provided they are good electrical conductors, it being equally obvious that the wires l may be made oi niet-als other than and,

for strength cannot.

1938, Serial No. 198,314

(Cl. lu-139) steel, provided they possess sulcient elasticity and tensile strength.

When tension is placed on such a cable, the wires i bear against each other, as contrasted to bearing against the softer wires 2, and since both wires l are of equal hardness, strength and toughness, no permanent deformation o the ca ble as a whole results. Since deformation is prem vented, sagging of the cable in service, such as might otherwise result from icefand wind loads, is not excessive at any time.

In the case of Figure 2, the same construction is provided except that the wires made o steel or other hard metalla, are smaller than the wires 2' made or" copper or other metal of good electrical conductivity, which are relatively sorter.

In Figure 3 the wires lb of harder :metal are shaped to provide relatively broad intercontacting surfaces Furthermore, the wires 2b oi softer metal are slightly shaped to more perfectly fit the interstices between the wires lb. All this is to the end of providing a bearing surface of greater area and, therefore, greater resistance to deformation during cable tensioning. ln addition, Figure 3 shows great r surface areas of contact o the wires which will lessen the tendency ot removal of the galvanized coating due to abrasion which will be 'more pronounced in the case oil single pointV contacts as provided by the con struction of Figures l and 2.

Figure carries the idea shown by Figure o even further, the harder wires lc being cmcisiden-1 ably tapered, as at 5l, and the soter wires 2 being provided with surfaces 5 fitting the surfaces d., Since the wires le possess considerable hardness their inner bearing surfaces Ba may be safely reduced in size. ln this particular construction, the harder wires bear against one another during cable tensioning, While the softer wires '2G bear 'ost the harder wires by way or very set up by 'axial wind forces but will be more ef-i- :Eected by the lateral wind forces under certainl weather conditions, that is, sieet and ice collecting on the wire form av vane of ice and when the wind strikes this vane of ice there will be a whip ping of the conductor. In this general construetion the proportioning of copper and s teel may be varied at will to meet specic mechanical andused, whereby to bring its elongation to about the same as steel v'rire cold drawn to provide it with apermanent elongation under tensile stress of about i1/2 per cent. The ordinary hard drawn copper Wire commerciallyavailable has an elongation of only about lil/2 per cent.

I claim:

1. A strand of intertwisted relatively softer and harder wires, the latter diametrically intercon- Ltacting and being symmetrical about the strand axis, and the softer wires being laidin the interstices between the harder Wires, the intercontasting surfaces of the harder wires being shaped to provide larger bearings than would be provided by cylindrical wires.

2. A strand of intertwisted relatively softer and harder wires, the latter diametrically intercontacting and being symmetrical about the strand axis, and the softer wires being laid in the interstices between the harder wires, the intercom tacting surfaces of all the wires being shaped to provide larger bearings than would be provided by cylindrical wires.

@WING W. EDWARDS. 

